World Cup ball will be on targetComment on this story
Paris - With every soccer World Cup, it seems, there is controversy about the ball - the Jabulani used in South Africa was said to be so unpredictable as to border on the “supernatural”.
The Fevernova used in South Korea and Japan in 2002 was said to be too light and bouncy, while some complained that Teamgeist used in Germany four years later was slippery.
On Thursday, scientists in Japan said the Brazuca which Adidas developed as the official ball for the 2014 World Cup in Brazil, should hit the mark.
It had a stable flight trajectory thanks to its shape and number of panels - a record-low six, they wrote in the Nature journal Scientific Reports.
Traditionally constructed from 32 panels, more recently the ball that is re-designed every four years for the sporting world's greatest spectacle, had fewer - Jabulani had eight panels and Teamgeist 14.
A pair of engineers at Japan's University of Tsukuba compared the aerodynamics of the Brazuca, Jabulani, Teamgeist, the Cafusa used in the 2013 Fifa Confederations Cup, and the conventional 32-panel ball in the laboratory.
They used wind tunnel tests and kicks with robot legs to measure drag, also called air resistance, and trajectory.
The tests showed that Jabulani, dubbed “supernatural” by Brazilian striker Luis Fabian, had, indeed, been an erratic ball.
Brazuca, on the other hand, had the lowest drag of all the balls tested, followed closely by the traditional 32-panel sphere.
These two balls also had the most stable trajectories.
Simon Choppin, a sports engineer at Sheffield Hallam University in England, said the findings meant the Brazuca would be more predictable for the players.
“It's much more likely to behave like the footballs they are used to play with.”
Choppin, who was not involved in the study, said the ball did not seem to have the problem of being too smooth, as some of its predecessors had been.
The smoother a ball, the more drag and other “unsteady” aerodynamic forces it experiences while travelling through the air, whereas a rougher ball surface, created by panel seams, for example, caused the opposite behaviour, he explained.
The seams on Brazuca, said Choppin, are deeper - thereby creating more surface roughness.
The research team said they have shown that a ball's characteristics can be used to predict its trajectory, which may be useful for coaching and design.
And while predictability of a ball is good for long, running passes and goalkeepers, not everyone may be happy with Brazuca's steady-does-it features.
Some strikers prefer a ball to dip and swerve, as it helps them confound the keeper.